document.write( "Question 831646: find sin theta if cos theta=1/2 and theta terminates in quadrant IV \n" ); document.write( "
Algebra.Com's Answer #501550 by KMST(5328)\"\" \"About 
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For angles terminating in quadrant IV, sine is negative and cosine is positive.
\n" ); document.write( "For any angle \"theta\" , \"sin%5E2%28theta%29+%2B+cos%5E2%28theta%29=1\" .
\n" ); document.write( "So, If \"cos%28theta%29=1%2F2\" ,
\n" ); document.write( "\"sin%5E2%28theta%29+%2B+%281%2F2%29%5E2=1\"
\n" ); document.write( "\"sin%5E2%28theta%29+%2B+1%2F4=1\"
\n" ); document.write( "\"sin%5E2%28theta%29=1-1%2F4\"
\n" ); document.write( "\"sin%5E2%28theta%29=3%2F4\"
\n" ); document.write( "Since we know that \"sin%28theta%29%3E0\" ,
\n" ); document.write( "\"sin%28theta%29=-sqrt%283%2F4%29\" is not a solution.
\n" ); document.write( "The solution is
\n" ); document.write( "\"sin%28theta%29=sqrt%283%2F4%29\"
\n" ); document.write( "\"highlight%28sin%28theta%29=sqrt%283%29%2F2%29\"
\n" ); document.write( "
\n" ); document.write( "NOTE:
\n" ); document.write( "We also know that one of the possible values of \"theta\" is \"-60%5Eo\" or \"-pi%2F3\",
\n" ); document.write( "because a 30-60-90 right triangle (one with angles measuring 30, 60, and 90 degrees) is half of an equilateral triangle>
\n" ); document.write( "
\n" ); document.write( "So for an equilateral triangle with side length of 1,
\n" ); document.write( "we get a right triangle where the leg opposite the \"30%5Eo\" angle (adjacent to the \"30%5Eo\" angle) measures \"1%2F2\" ,
\n" ); document.write( "meaning that \"sin%2830%5Eo%29=cos%2860%5Eo%29=1%2F2\" .
\n" ); document.write( "
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